In a driving force controller for an electric vehicle, a motor torque command value set based on a required driving force of a driver (target driving force) is corrected to suppress a vibration (a torsional vibration) generated from a torsion of a drive system (in the present application, a term “driving force” shall be used as synonymous with a “drive shaft torque”). For example, the driving force controller calculates, as a target vehicle speed, a vehicle speed in a case where a motor torque command value is applied to a vehicle model by use of an ideal vehicle model assuming that a drive system is a rigid body that does not generate torsion. Then, the driving force controller obtains deviation between the target vehicle speed and the actual vehicle speed, and calculates a correction value to reduce the deviation. The driving force controller thus obtains a final motor torque command value by adding the correction value to the motor torque command value.
In the ideal vehicle model, a disturbance torque such as: a running resistance torque such as air resistance; and a braking torque caused by braking, is not inputted. Thus, such a disturbance torque is not reflected on the target vehicle speed outputted from the vehicle model and the correction value computed based on the target vehicle speed. As a result, although the torsional vibration can be suppressed by the correction value, there has been a problem that an actual driving force is deviated from the required driving force of the driver because, when running resistance is generated or at the time of braking, such an excessive driving force is generated so as to cancel out the running resistance torque or the braking torque caused by braking.
In Patent Literature 1, as a method for suppressing such increase of the driving force resulting from the disturbance torque, an external input estimator has been proposed for estimating the disturbance torque, subtracting the disturbance torque from a motor request torque in advance when computing the target vehicle speed and the target motor speed, and computing the target rotational speed with the disturbance torque taken into consideration.